In general, the time to have a 4D ultrasound is between 24 weeks of intrauterine pregnancy and 28 weeks of intrauterine pregnancy. 4D ultrasound adds the time dimension parameter to the normal 3D ultrasound, thus allowing a clearer view of the fetus in the womb. For 4D ultrasound, it is recommended that pregnant women undergo it between 24 and 28 weeks of pregnancy. If 4D ultrasound is done too early, the images seen are not clear enough because the fetus is relatively small and has little subcutaneous fat. And after 30 weeks of intrauterine pregnancy, the head of some babies will enter the pelvis and the fetus is larger, for which the whole body of the baby may not be seen. Therefore, 4D ultrasound is recommended to be performed between 24 weeks of intrauterine pregnancy and 28 weeks of intrauterine pregnancy. Having 4D ultrasound can rule out fetal malformations, such as cleft lip and palate, facial malformations, hydrocephalus, microcephaly, etc.